The present invention relates to methods of treating long-interval and high-contrast permeability subterranean formations with diverting fluids.
Subterranean wells (such as hydrocarbon producing wells, water producing wells, and injection wells) are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing treatments, a viscous fracturing fluid, which may also function as a carrier fluid, is pumped into a portion of a subterranean formation at a rate and pressure such that the subterranean formation breaks down and one or more fractures are formed. Typically, particulate solids, such as graded sand, are suspended in a portion of the fracturing fluid and then deposited in the fractures. These particulate solids, or “proppant particulates,” serve to prevent the fractures from fully closing once the hydraulic pressure is removed. By keeping the fracture from fully closing, the proppant particulates aid in forming conductive paths through which fluids may flow.
Achieving adequate fracture penetration, and thus adequate hydrocarbon production, in a subterranean formation often requires the use of diverting agents. The purpose of the diverting agents is to prevent substantial loss of the liquid portion of treatment fluids into an undesired portion of a subterranean formation. Diverting agents are intended to divert treatment fluids from a high permeability zone in a subterranean formation to a lower permeability zone to prevent the buildup of solid material or filter cake that may form on the high permeability zones. Such buildup may result in stuck pipe, decreased hydrocarbon production, and other drilling and fracturing problems. Diverting agents may be used prior to, during, or after fracturing a subterranean formation. The effectiveness of a diverting agent depends on a number of factors, including temperature, wellbore length, and permeability of the subterranean formation.
Traditional diverting agents may be less effective when used to treat long-interval and/or high-contrast permeability formations. In long-interval formations, traditional diverting agents may be exhausted prior to reaching target portions of the formation. Long-interval formations are additionally more likely to having high-contrast permeability portions. In high-contrast permeability formations, low permeability and high permeability portions of the formation are adjacent to or in fluid communication with one another. Traditional diverting agents are designed to target these high permeability zones, diverting treatment fluids to allow for uniform injection and/or penetration of a treatment fluid over the entire interval length. A need, therefore, for more effective diverting agents over long-interval formations and high-contrast permeability formations may be of value to one of ordinary skill in the art.